1. Field of the Invention
The present invention relates to a sheet sorter for distributing document sheets, supplied from an image forming apparatus such as a copier, a duplicator or a facsimile, in successive manner into receiving trays or bins.
2. Description of the Prior Art
It has been desired to reduce the dimension and weight of the sheet sorter for distributing and classifying the original documents and copying sheets (hereinafter collectively referred to as "sheet") continuously ejected from a copier. Dimensional reduction is however difficult in a sheet sorter with a number of bin trays since such trays require a large volume. Such dimensional reduction is rendered possible by maintaining the gaps between the mutually parallel trays wider only at the sheet receiving position but narrower in other positions, thereby saving the entire volume. However, in a sheet sorter in which the sheets are driven at a high speed, it has been difficult to effect the gap widening motion of the trays in secure manner with low noise and with low power consumption, corresponding to the high-speed transportation of the sheets.